Pavlakis et al. (2015)

Brain Imaging and Electrophysiology Biomarkers: Is There a Role in Poverty and Education Outcome Research?

Background information: There are several reasons why socioeconomic status (SES) mayimpact brain development in poor children.This may be a result of stress caused by poverty, pre-natal conditions, parent-child interactions, and fewer books and educational toys in the home. Experiments with mice suggested that mice who are stressed when very young might perform less well on cognitive tasks as adults. There was also a shrinking of the hippocampus in adult mice that were stressed in childhood. Research in both animals and humans suggests that stressful experiences may be associated with reductions in hippocampus size.

Prekindergarten educational interventions represent a popular approach to improving educational outcomes, especially in children from poor households. Children from lower socioeconomic groups are at increased risk for delays in cognitive development, and these differences often develop before kindergarten. Early interventions have been proposed, but there is a need for more information on their effectiveness. Assessing differences in brain structure and function according to poverty levels may help to track the neurobiological basis underlying children’s cognitive improvement.

Aim: To assess socioeconomic differences in brain structure and function, in order to track the neurobiological basis underlying children’s cognitive improvement after early interventions.

Method: A review of the neuroimaging and electrophysiology literature was conducted to evaluate what is known about differences in brain structure and function as assessed by magnetic resonance imaging (MRI), functional MRI (fMRI) and electroencephalogram imaging (EEG) among children from poor and better-off households. The researchers found 23 relevant published studies and explored the relationship between SES (defined as parental income and/or education and/or occupation) and brain MRIs, fMRIs and EEGs in the context of schooling.

Results: All of the surveyed literature, apart from one study which showed no volume change in the brain, recorded structural and functional differences in the brains of children from a low SES and adults who had been poor in childhood, when compared with children and adults from a higher SES.

The results are complex to interpret, but differences were found in three crucial regions, depending on the task and the method of imaging: language (left hemisphere), cognitive control (pre- frontal cortex), and memory (hippocampus). These three domains are crucial to school success. These differences included less grey matter in the temporal lobe region, including the hippocampus (related to memory), reduced activity in the pre-frontal lobe (to do with attention) and amygdala (emotional engagement) when focused on a task, and later development of neurons in the language regions of the brain.

Regarding the effect of early intervention, one study of 143 lower SES children showed that family-based interventions not only improved cognitive skills in children but also resulted in changes in EEGs of brain waves during an attention task

Conclusion: Much more research is needed, butthe studies reviewed show that there are SES disparities that may underlie known socioeconomic disparities in cognitive development, although the etiology is likely a complex interaction of multiple factors. [Despite its intention to measure the effects of early intervention programmes, the study ends with a suggestion that EEG (which is the cheapest of the methods) be employed with a small number of children to do just that.]

Evaluation:

Strengths of the study: A meta-analysis like this is useful for gaining an overview of the methods and results of previous research unto neurological changes in the brains of children being raised in poverty.

Limitations of the study: The data set is so large and so disparate (23 studies, using fMRI, MRI and EEG scans in different ways with different numbers and ages of children and adults of differing SES) that a summary is difficult. While there is a correlation between children raised in poverty and less dense grey matter in the temporal lobe, including the hippocampus, and lower brain activity in other regions, the researchers admit that there is likely to be a large interaction of social and biological factors that underlie these changes. Only one study out of the 23 examined mentioned neurological changes as a result of early intervention.

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